Perpendicular magnetic recording system with medium having thin soft underlayer and recording head having thick-throat trailing shield

a perpendicular magnetic recording and data storage technology, applied in the field of perpendicular magnetic recording data storage systems, can solve the problems of high write field required to reverse the magnetization in the rl, difficult and costly to manufacture large numbers of these types of perpendicular magnetic recording hdds, and requires additional materials. , to achieve the effect of narrowing the magnetic transition, high write field gradient, and low magnetic permeability
US7532432B2Inactive Publication Date: 2009-05-12WESTERN DIGITAL TECH INC
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Patent Information

Authority / Receiving Office
US ¡ United States
Patent Type
Patents(United States)
Current Assignee / Owner
WESTERN DIGITAL TECH INC
Publication Date
2009-05-12
Estimated Expiration
Not applicable ¡ inactive patent

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Abstract

A perpendicular magnetic recording data storage system combines a perpendicular medium that has a thin low-magnetic-permeability or “soft” underlayer (SUL) with a recording head that has a trailing shield (TS) with a thick throat height, i.e., a thickness in a direction orthogonal to the recording layer of the medium. The SUL is thin enough and has a low enough magnetic permeability to become saturated in a region beneath the trailing gap of the head during writing, but the throat height of the TS is thick enough to prevent the TS from becoming magnetically saturated during writing. The magnetic saturation of the SUL during writing changes the magnetic reluctance such that more of the magnetic flux going through the SUL changes direction (“field undershoot”) and goes to the TS. If the permeability of the SUL is so low (e.g., close to unity) that the SUL does not magnetically saturate, field undershoot may still occur because the reluctance from the SUL to the TS is still smaller than the reluctance from the SUL to the return pole (RP). Field undershoot enables a high write field gradient, which results in narrower magnetic transitions.
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Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to perpendicular magnetic recording data storage systems, and more particularly to a system that uses a medium with a recording layer formed over a “soft” or relatively low-coercivity magnetically permeable underlayer, and a recording head with a single write pole and a trailing shield.

[0003] 2. Description of the Related Art

[0004] Perpendicular magnetic recording, wherein the recorded bits are stored in a perpendicular or out-of-plane orientation in the recording layer, is a promising path toward ultra-high recording densities in data storage systems, such as hard disk drives (HDDs). One type of system uses a recording head with a single write pole (WP) and a “dual-layer” recording disk with the perpendicular magnetic data recording layer (RL) formed over a “soft” or relatively low-coercivity magnetically permeable underlayer (SUL). The SUL serves as a return path for magnetic flux from t...

Claims

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